MovieSceneInterpolation.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Misc/FrameNumber.h"
#include "Misc/FrameTime.h"
#include "Misc/FrameRate.h"
#include "Misc/TVariant.h"
 
 
namespace UE::MovieScene::Interpolation
{
 
struct FInvalidValue;
struct FConstantValue;
struct FLinearInterpolation;
struct FQuadraticInterpolation;
struct FCubicInterpolation;
struct FQuarticInterpolation;
struct FCubicBezierInterpolation;
struct FWeightedCubicInterpolation;
 
 
template<typename T, int MinN>
struct TInterpSolutions
{
    template<int N>
    TInterpSolutions(T (&In)[N]) requires (N >= MinN)
        : Array(In)
    {}
 
    template<int OtherN>
    operator TInterpSolutions<T, OtherN>() const requires (OtherN <= MinN)
    {
        return TInterpSolutions<T, OtherN>(Array);
    }
 
    T& operator[](int Index) const
    {
        check(Index<MinN);
        return Array[Index];
    }
 
private:
 
    template<typename U, int OtherN>
    friend struct TInterpSolutions;
 
    explicit TInterpSolutions(T* InArray)
        : Array(InArray)
    {}
 
    T* Array;
};
 
 
 
struct FInterpolationExtents
{
    double MinValue = std::numeric_limits<double>::max();
    double MaxValue = std::numeric_limits<double>::lowest();
 
    FFrameTime MinValueTime;
    FFrameTime MaxValueTime;
 
    MOVIESCENE_API bool IsValid() const;
 
    MOVIESCENE_API void AddPoint(double Value, FFrameTime Time);
 
    MOVIESCENE_API void Combine(const FInterpolationExtents& Other);
};
 
struct FInvalidValue
{
};
 
 
struct FConstantValue
{
    double Value;
 
    FFrameNumber Origin;
 
    UE_DEPRECATED(5.5, "Please provide an origin. This is required for Integral() to work correctly.")
    FConstantValue(double InValue)
        : FConstantValue(0, InValue)
    {}
 
    FConstantValue(FFrameNumber InOrigin, double InValue)
        : Value(InValue)
        , Origin(InOrigin)
    {}
 
    MOVIESCENE_API FConstantValue Derivative() const;
    MOVIESCENE_API FLinearInterpolation Integral(double ConstantOffset = 0.0) const;
};
 
struct FLinearInterpolation
{
    double Coefficient;
    double Constant;
    FFrameNumber Origin;
 
    FLinearInterpolation(FFrameNumber InOrigin, double InCoefficient, double InConstant)
        : Coefficient(InCoefficient)
        , Constant(InConstant)
        , Origin(InOrigin)
    {}
 
    MOVIESCENE_API double Evaluate(FFrameTime InTime) const;
 
    MOVIESCENE_API int32 Solve(double Value, TInterpSolutions<FFrameTime, 1> OutResults) const;
 
    MOVIESCENE_API int32 SolveWithin(FFrameTime Start, FFrameTime End, double Value, TInterpSolutions<FFrameTime, 1> OutResults) const;
 
    MOVIESCENE_API FConstantValue Derivative() const;
 
    MOVIESCENE_API FQuadraticInterpolation Integral(double ConstantOffset = 0.0) const;
};
 
struct FQuadraticInterpolation
{
    double A, B;
    double Constant;
    FFrameNumber Origin;
 
    FQuadraticInterpolation(FFrameNumber InOrigin, double InA, double InB, double InConstant)
        : A(InA), B(InB)
        , Constant(InConstant)
        , Origin(InOrigin)
    {}
 
    MOVIESCENE_API double Evaluate(FFrameTime InTime) const;
 
    MOVIESCENE_API int32 Solve(double Value, TInterpSolutions<FFrameTime, 2> OutResults) const;
 
    MOVIESCENE_API int32 SolveWithin(FFrameTime Start, FFrameTime End, double Value, TInterpSolutions<FFrameTime, 2> OutResults) const;
 
    MOVIESCENE_API FLinearInterpolation Derivative() const;
 
    MOVIESCENE_API FCubicInterpolation Integral(double ConstantOffset = 0.0) const;
};
 
struct FCubicInterpolation
{
    double A, B, C;
    double Constant;
 
    double DX;
 
    FFrameNumber Origin;
 
    FCubicInterpolation(FFrameNumber InOrigin, double InA, double InB, double InC, double InConstant, double InDX = 1.0)
        : A(InA), B(InB), C(InC)
        , Constant(InConstant)
        , DX(InDX)
        , Origin(InOrigin)
    {}
 
    MOVIESCENE_API double Evaluate(FFrameTime InTime) const;
 
    MOVIESCENE_API int32 Solve(double Value, TInterpSolutions<FFrameTime, 3> OutResults) const;
 
    MOVIESCENE_API int32 SolveWithin(FFrameTime Start, FFrameTime End, double Value, TInterpSolutions<FFrameTime, 3> OutResults) const;
 
    MOVIESCENE_API FQuadraticInterpolation Derivative() const;
 
    MOVIESCENE_API FQuarticInterpolation Integral(double ConstantOffset = 0.0) const;
};
 
struct FQuarticInterpolation
{
    double A, B, C, D;
    double Constant;
 
    double DX;
 
    FFrameNumber Origin;
 
    FQuarticInterpolation(FFrameNumber InOrigin, double InA, double InB, double InC, double InD, double InConstant, double InDX = 1.0)
        : A(InA), B(InB), C(InC), D(InD)
        , Constant(InConstant)
        , DX(InDX)
        , Origin(InOrigin)
    {}
 
    MOVIESCENE_API double Evaluate(FFrameTime InTime) const;
 
    MOVIESCENE_API int32 Solve(double Value, TInterpSolutions<FFrameTime, 4> OutResults) const;
 
    MOVIESCENE_API int32 SolveWithin(FFrameTime Start, FFrameTime End, double Value, TInterpSolutions<FFrameTime, 4> OutResults) const;
 
    MOVIESCENE_API FCubicInterpolation Derivative() const;
};
 
struct FCubicBezierInterpolation
{
    double DX;
    double P0, P1, P2, P3;
    FFrameNumber Origin;
 
    MOVIESCENE_API FCubicBezierInterpolation(
        FFrameNumber InOrigin,
        double InDX,
        double InStartValue,
        double InEndValue,
        double InStartTangent,
        double InEndTangent);
 
    MOVIESCENE_API FCubicInterpolation AsCubic() const;
 
    MOVIESCENE_API double Evaluate(FFrameTime InTime) const;
 
    MOVIESCENE_API int32 Solve(double InValue, TInterpSolutions<FFrameTime, 4> OutResults) const;
 
    MOVIESCENE_API FQuadraticInterpolation Derivative() const;
 
    MOVIESCENE_API FQuarticInterpolation Integral(double ConstantOffset = 0.0) const;
};
 
struct FWeightedCubicInterpolation
{
    double DX;
    double StartKeyValue;
    double NormalizedStartTanDX;
    double StartKeyTanY;
    double StartWeight;
 
    double EndKeyValue;
    double NormalizedEndTanDX;
    double EndKeyTanY;
    double EndWeight;
 
    FFrameNumber Origin;
 
    FWeightedCubicInterpolation(
        FFrameRate TickResolution,
        FFrameNumber InOrigin,
 
        FFrameNumber StartTime, 
        double StartValue,
        double StartTangent,
        double StartTangentWeight,
        bool bStartIsWeighted,
 
        FFrameNumber EndTime, 
        double EndValue,
        double EndTangent,
        double EndTangentWeight,
        bool bEndIsWeighted);
 
    double Evaluate(FFrameTime InTime) const;
 
 
    MOVIESCENE_API int32 Solve(double Value, TInterpSolutions<FFrameTime, 4> OutResults) const;
};
 
struct FCachedInterpolationRange
{
    static MOVIESCENE_API FCachedInterpolationRange Empty();
    static MOVIESCENE_API FCachedInterpolationRange Finite(FFrameNumber InStart, FFrameNumber InEnd);
    static MOVIESCENE_API FCachedInterpolationRange Infinite();
 
    static MOVIESCENE_API FCachedInterpolationRange Only(FFrameNumber InTime);
    static MOVIESCENE_API FCachedInterpolationRange From(FFrameNumber InStart);
    static MOVIESCENE_API FCachedInterpolationRange Until(FFrameNumber InEnd);
 
    FFrameNumber Clamp(FFrameNumber In) const
    {
        return FMath::Clamp(
            In.Value,
            Start.Value,
            End.Value);
    }
    FFrameTime Clamp(FFrameTime In) const
    {
        return FMath::Clamp(
            In,
            FFrameTime(Start),
            FFrameTime(End));
    }
 
    MOVIESCENE_API bool Contains(FFrameNumber FrameNumber) const;
 
    MOVIESCENE_API bool IsEmpty() const;
 
    FFrameNumber Start;
    FFrameNumber End;
};
 
struct FCachedInterpolation
{
    MOVIESCENE_API FCachedInterpolation();
    MOVIESCENE_API FCachedInterpolation(const FCachedInterpolationRange& InRange, const FConstantValue& Constant);
    MOVIESCENE_API FCachedInterpolation(const FCachedInterpolationRange& InRange, const FLinearInterpolation& Linear);
    MOVIESCENE_API FCachedInterpolation(const FCachedInterpolationRange& InRange, const FQuadraticInterpolation& Quadratic);
    MOVIESCENE_API FCachedInterpolation(const FCachedInterpolationRange& InRange, const FCubicInterpolation& Cubic);
    MOVIESCENE_API FCachedInterpolation(const FCachedInterpolationRange& InRange, const FQuarticInterpolation& Quartic);
    MOVIESCENE_API FCachedInterpolation(const FCachedInterpolationRange& InRange, const FCubicBezierInterpolation& CubicBezier);
    MOVIESCENE_API FCachedInterpolation(const FCachedInterpolationRange& InRange, const FWeightedCubicInterpolation& WeightedCubic);
 
    MOVIESCENE_API bool IsValid() const;
 
    MOVIESCENE_API bool IsCacheValidForTime(FFrameNumber FrameNumber) const;
 
    MOVIESCENE_API FCachedInterpolationRange GetRange() const;
 
    MOVIESCENE_API bool Evaluate(FFrameTime FrameTime, double& OutResult) const;
 
    MOVIESCENE_API TOptional<FCachedInterpolation> ComputeIntegral(double ConstantOffset = 0.0) const;
 
    MOVIESCENE_API TOptional<FCachedInterpolation> ComputeDerivative() const;
 
    MOVIESCENE_API int32 InverseEvaluate(double InValue, TInterpSolutions<FFrameTime, 4> OutResults) const;
 
    MOVIESCENE_API FInterpolationExtents ComputeExtents(FFrameTime From, FFrameTime To) const;
    MOVIESCENE_API FInterpolationExtents ComputeExtents() const;
 
    MOVIESCENE_API void Offset(double Amount);
 
private:
 
    TVariant<FInvalidValue,
        FConstantValue,
        FLinearInterpolation,
        FQuadraticInterpolation,
        FCubicInterpolation,
        FQuarticInterpolation,
        FCubicBezierInterpolation,
        FWeightedCubicInterpolation> Data;
 
    FCachedInterpolationRange Range;
};
 
} // namespace UE::MovieScene